Field of the Invention
The present invention relates generally to a sealing device for the closure of puncture holes in blood vessels and, in particular, to a sealing device that does not require a sheath change and is simple to operate.
Technical Background
For many diagnostic and interventional procedures it is necessary to access arteries or veins. Vessel access is accomplished either by direct vision or percutaneously. In either case, the target vessel is punctured with a hollow needle containing a tracer wire. When the intravascular positioning of the tracer wire has been verified, the hollow needle is removed leaving the tracer wire. Next, a sheath containing a dilator is pushed in over the tracer wire. The dilator enlarges the puncture opening to facilitate the insertion of the larger diameter sheath into the blood vessel. The sheath usually consists of a hollow tube with an open distal end and a hemostatic valve at a proximal end, which remains outside the body and blood vessel. The hemostatic valve is made of a compliant material and is designed in such a way as to allow devices such as catheters to be inserted and withdrawn from the blood vessel with minimal blood loss. After the sheath has been inserted into the blood vessel, the dilator is removed leaving a clear passageway in the sheath for the catheter. The sheath is removed from the blood vessel after the procedure is finished resulting in bleeding at the puncture site that must be staunched.
Traditionally, pressure is applied at the puncture site to allow the blood to clot, thereby stopping the bleeding. Depending on the amount of anticoagulants that may have been administered to the patient during and prior to the procedure, the time that the pressure must be maintained varies from 15 minutes to more than an hour. Once bleeding has stopped, a pressure bandage is placed over the site of the puncture in an attempt to protect the integrity of the clot. The pressure bandage must remain in place for some time, usually from 8 to 24 hours. During this period of time the patient must remain in bed, sometimes requiring an overnight hospital stay.
To shorten the length of time required for the patient to become ambulatory and to lessen complications that may arise from the traditional method of sealing the opening, several closure devices have been developed. One such device, as described in U.S. Pat. No. 5,620,461, is a foldable sheet with an attachment thread that is inserted into the opening in the blood vessel and an arresting element that is applied over the attachment element against the outside of the blood vessel. Another such device is described in U.S. Pat. Nos. 6,045,569 and 6,090,130, and includes an absorbable collagen plug cinched down against an absorbable intervascular anchor via an absorbable suture. The absorbable intervascular anchor has an elongated rectangular shape that requires it to be inserted into the puncture wound with its longitudinal axis approximately parallel to the sheath axis. This requires it to be rotated ninety degrees after insertion so that blood flow obstruction is minimized. A specially designed sheath is necessary to assure proper rotation, thus resulting in an otherwise unnecessary sheath change. The long dimension of the anchor is thus larger than the cannula inside diameter (ID) and the width is smaller than the ID. The collagen plug is in an elongated state prior to deployment and is forced into a ball shape via a slipknot in the suture, which passes through the collagen, and a tamper that applies a distal force to it. The anchor acts as a support for the suture cinch which forces the collagen ball shape up against the exterior blood vessel wall and the anchor. Blood flow escaping around the anchor is slowed down and absorbed by the collagen material and thus forms a clotting amalgamation outside the blood vessel that is more stable than the traditional method of a standalone clot. The added robustness of the amalgamation clot allows earlier ambulation of the patient.
The device raises several issues. It is not a true sealing device but rather a clotting enhancement device, as opposed to a device with two flat surfaces exerting sealing pressure on both the interior and exterior of the blood vessel, a much more reliable technique. In either case, bleeding occurs during the time between removal of the sheath and full functionality of the deployed device. Thus “instant” sealing pressure from two flat surfaces is desirable over a method that relies to any extent on clotting time. One such device is disclosed by Bates et. al. in U.S. Pat. No. 8,080,034. The '034 device comprises an internal sealing surface pivoting on a rigid post to accommodate the longitudinal dimension of the seal inside the sheath ID. The exterior seal (second clamping member) is slidable along the rigid post and pivotal such that it, along with the internal seal, sandwiches the wall of the blood vessel via a locking ratchet. One problem with this design is that the pivoting feature increases the cross-sectional dimension of the seal thus requiring a larger diameter sheath than would be otherwise needed. In addition, the pivoting internal seal has no means to assure that the seal pivots to the correct sealing position as the ratchet closes. This could cause the internal seal to exit the blood vessel in the collapsed configuration as the user withdraws the deploying device. In addition no specific mechanism for the release of the seals from the deployment instrument is disclosed, other than a general statement “any known means.”
The seals are released by the user cutting the suture thread in the device described in U.S. Pat. No. 6,045,569.
It is known that the opening in the blood vessel closes to some extent after the sheath is removed, thus allowing smaller seal surfaces than would otherwise be required. What is less known is that the opening does not close as quickly as a truly elastic material such as natural rubber or latex. For this reason, seal surfaces of closure devices that are activated in less than a second, or perhaps even longer, after sheath removal must be physically larger than the sheath outside diameter to avoid embolization of the seals because of the delayed blood vessel closure. The design of seals that are deployed through a sheath ID with dimensions larger than the sheath OD upon deployment is a challenge since the preferred material for seals are bio-absorbable and thus have limited mechanical properties.
An active sealing assembly comprising solid, flat interior and exterior elements that sandwich the blood vessel wall to insure hemostasis and yet have major dimensions that exceed the interior diameter of the introducer sheath to compensate for slow, partial closure of the wound upon removal of the sheath thereby minimizing leakage and avoiding embolization of the sealing components offers a design challenge. Components can be introduced through the sheath internal diameter (ID) longitudinally and rotated into a position adjacent to the blood vessel wall such that the longitudinal dimension exceeds the sheath ID with little or no concern regarding the mechanical properties of the material. The devices in the '461 and '034 patents are examples. As noted previously, these solutions have severe limitations.
Another method of accomplishing the desired result of obtaining a deployed seal larger than the sheath ID is to fold the seal elements while they traverse the sheath ID and reopen them upon deployment. Optimally, the major dimension of the seal elements should be 1.5 to 2 times larger than the outside diameter of the sheath. The '569 Patent discloses an external seal made of an elongated pliable collagen plug that swells upon absorbing blood leaking from the wound and is tamped into more or less of a ball larger than the opening of the wound. The internal seal is inserted longitudinally through a special sheath which, with the aid of an attachment thread, rotates the seal parallel to the blood vessel surface.
The '569 device requires removing the catheter sheath and replacing it with a custom sheath prior to deployment, resulting in additional blood loss. The tamping force used to deploy the collagen against the anchor is left to the surgeon's feel, sometimes resulting in inadequate deployment and other times resulting in the collagen being pushed through the puncture wound and into the blood vessel along with the anchor. Inadequate tamping results in excessive bleeding with the potential for painful hematoma and over tamping can require a surgical procedure to remove the device from the blood vessel lumen. In addition, the absorption rate of the suture, the collagen, and the anchor may be different owing to the fact that they are formed from different materials, sometimes resulting in the premature detachment of the anchor, which can move freely in the blood stream and become lodged in the lower extremities of the body, again requiring surgical removal.
U.S. Pat. No. 5,350,399 discloses umbrella-shaped foldable bio-compatible seals that are not bioabsorbable.
It would be desirable therefore to provide a vessel-sealing device that actually seals the blood vessel and does not rely on the clotting of the blood. It is also desirable to provide a closure device that is deployable through the catheter sheath with minimal steps requiring less than 2 minutes for hemostasis. It would be also desirable to provide a reliable, active vessel-sealing device comprising a bio-absorbable seal assembly with deployed major dimensions larger than the sheath outside diameter.